#include <qevent.h>
#include "qwinwidget.h"
#include <qt_windows.h>
#include <QtWidgets/QApplication>

#include <QWindow>
#include <qpa/qplatformnativeinterface.h>

/*!
    \class QWinWidget qwinwidget.h
    \brief The QWinWidget class is a Qt widget that can be child of a
    native Win32 widget.

    The QWinWidget class is the bridge between an existing application
    user interface developed using native Win32 APIs or toolkits like
    MFC, and Qt based GUI elements.

    Using QWinWidget as the parent of QDialogs will ensure that
    modality, placement and stacking works properly throughout the
    entire application. If the child widget is a top level window that
    uses the \c WDestructiveClose flag, QWinWidget will destroy itself
    when the child window closes down.

    Applications moving to Qt can use QWinWidget to add new
    functionality, and gradually replace the existing interface.
*/

/*!
    Creates an instance of QWinWidget. \a hParentWnd is the handle to
    the native Win32 parent. If a \a parent is provided the object is
    owned by that QObject. \a f is passed on to the QWidget constructor.
*/
QWinWidget::QWinWidget(HWND hParentWnd, QObject *parent, Qt::WindowFlags f)
: QWidget(0, f), hParent(hParentWnd), prevFocus(0), reenable_parent(false)
{
    if (parent)
        QObject::setParent(parent);

    init();
}

void QWinWidget::init()
{
    Q_ASSERT(hParent);

    if ( hParent ) {
        setProperty("_q_embedded_native_parent_handle", (WId)hParent);
        setWindowFlags(Qt::FramelessWindowHint);

        // make the widget window style be WS_CHILD so SetParent will work
        SetWindowLong((HWND)winId(), GWL_STYLE, WS_CHILD | WS_CLIPCHILDREN | WS_CLIPSIBLINGS);

        SetParent((HWND)winId(), hParent);
        QEvent e(QEvent::EmbeddingControl);
        QApplication::sendEvent(this, &e);
    }
}

/*!
    Destroys this object, freeing all allocated resources.
*/
QWinWidget::~QWinWidget()
{
}

/*!
    Returns the handle of the native Win32 parent window.
*/
HWND QWinWidget::parentWindow() const
{
    return hParent;
}

/*!
    \reimp
*/
void QWinWidget::childEvent(QChildEvent *e)
{
    QObject *obj = e->child();
    if (obj->isWidgetType())
    {
        if (e->added())
        {
            if (obj->isWidgetType())
            {
                obj->installEventFilter(this);
            }
        }
        else if (e->removed() && reenable_parent)
        {
            reenable_parent = false;
            EnableWindow(hParent, true);
            obj->removeEventFilter(this);
        }
    }
    QWidget::childEvent(e);
}

/*! \internal */
void QWinWidget::saveFocus()
{
    if (!prevFocus)
        prevFocus = ::GetFocus();
    if (!prevFocus)
        prevFocus = parentWindow();
}

/*!
    Shows this widget. Overrides QWidget::show().

    \sa showCentered()
*/
void QWinWidget::show()
{
    saveFocus();
    QWidget::show();
}

/*!
    Centers this widget over the native parent window. Use this
    function to have Qt toplevel windows (i.e. dialogs) positioned
    correctly over their native parent windows.

    \code
    QWinWidget qwin(hParent);
    qwin.center();

    QMessageBox::information(&qwin, "Caption", "Information Text");
    \endcode

    This will center the message box over the client area of hParent.
*/
void QWinWidget::center()
{
    const QWidget *child = findChild<QWidget*>();
    if (child && !child->isWindow())
    {
        qWarning("QWinWidget::center: Call this function only for QWinWidgets with toplevel children");
    }
    RECT r;
    GetWindowRect(hParent, &r);
    setGeometry((r.right-r.left)/2+r.left, (r.bottom-r.top)/2+r.top,0,0);
}

/*!
    \obsolete

    Call center() instead.
*/
void QWinWidget::showCentered()
{
    center();
    show();
}

/*!
    Sets the focus to the window that had the focus before this widget
    was shown, or if there was no previous window, sets the focus to
    the parent window.
*/
void QWinWidget::resetFocus()
{
    if (prevFocus)
        ::SetFocus(prevFocus);
    else
        ::SetFocus(parentWindow());
}

/*! \reimp
*/
bool QWinWidget::nativeEvent(const QByteArray &, void *message, long *)
{
    MSG *msg = (MSG *)message;

    if (msg->message == WM_SETFOCUS)
    {
        Qt::FocusReason reason;
        if (::GetKeyState(VK_LBUTTON) < 0 || ::GetKeyState(VK_RBUTTON) < 0)
            reason = Qt::MouseFocusReason;
        else if (::GetKeyState(VK_SHIFT) < 0)
            reason = Qt::BacktabFocusReason;
        else
            reason = Qt::TabFocusReason;
        QFocusEvent e(QEvent::FocusIn, reason);
        QApplication::sendEvent(this, &e);
    }

    return false;
}

/*!
    \reimp
*/
bool QWinWidget::eventFilter(QObject *o, QEvent *e)
{
    QWidget *w = (QWidget*)o;

    switch (e->type())
    {
    case QEvent::WindowDeactivate:
        if (w->isModal() && w->isHidden())
            BringWindowToTop(hParent);
        break;

    case QEvent::Hide:
        if (reenable_parent)
        {
            EnableWindow(hParent, true);
            reenable_parent = false;
        }
        resetFocus();
        if (w->testAttribute(Qt::WA_DeleteOnClose) && w->isWindow())
            deleteLater();
        break;

    case QEvent::Show:
        if (w->isWindow())
        {
            saveFocus();
            hide();
            if (w->isModal() && !reenable_parent)
            {
                EnableWindow(hParent, false);
                reenable_parent = true;
            }
        }
        break;

    case QEvent::Close:
        ::SetActiveWindow(hParent);
        if (w->testAttribute(Qt::WA_DeleteOnClose))
            deleteLater();
        break;

    default:
        break;
    }

    return QWidget::eventFilter(o, e);
}

/*! \reimp
*/
void QWinWidget::focusInEvent(QFocusEvent *e)
{
    QWidget *candidate = this;

    switch (e->reason())
    {
    case Qt::TabFocusReason:
    case Qt::BacktabFocusReason:
        while (!(candidate->focusPolicy() & Qt::TabFocus))
        {
            candidate = candidate->nextInFocusChain();
            if (candidate == this)
            {
                candidate = 0;
                break;
            }
        }
        if (candidate)
        {
            candidate->setFocus(e->reason());
            if (e->reason() == Qt::BacktabFocusReason || e->reason() == Qt::TabFocusReason)
            {
                candidate->setAttribute(Qt::WA_KeyboardFocusChange);
                candidate->window()->setAttribute(Qt::WA_KeyboardFocusChange);
            }
            if (e->reason() == Qt::BacktabFocusReason)
                QWidget::focusNextPrevChild(false);
        }
        break;
    default:
        break;
    }
}

/*! \reimp
*/
bool QWinWidget::focusNextPrevChild(bool next)
{
    QWidget *curFocus = focusWidget();
    if (!next)
    {
        if (!curFocus->isWindow())
        {
            QWidget *nextFocus = curFocus->nextInFocusChain();
            QWidget *prevFocus = 0;
            QWidget *topLevel = 0;
            while (nextFocus != curFocus)
            {
                if (nextFocus->focusPolicy() & Qt::TabFocus)
                {
                    prevFocus = nextFocus;
                    topLevel = 0;
                }
                else if (nextFocus->isWindow())
                {
                    topLevel = nextFocus;
                }
                nextFocus = nextFocus->nextInFocusChain();
            }

            if (!topLevel)
            {
                return QWidget::focusNextPrevChild(false);
            }
        }
    }
    else
    {
        QWidget *nextFocus = curFocus;
        while (1)
        {
            nextFocus = nextFocus->nextInFocusChain();
            if (nextFocus->isWindow())
                break;
            if (nextFocus->focusPolicy() & Qt::TabFocus)
            {
                return QWidget::focusNextPrevChild(true);
            }
        }
    }

    ::SetFocus(hParent);
    return true;
}
